(Results) In this series, CFS was useful to monitor general fatigue after introduction of enzalutamide. General fatigue after introduction of enzalutamide mainly consisted of physical fatigue, and improved in two of the three cases included in this study. However, enzalutamide was discontinued in one patient due to general fatigue. Fourteen of our 31 previous CRPC cases developed general fatigue after introduction of enzalutamide. The mean periods of enzalutamide prescription were 265.6, 173.2, and 193.0 days in the non-general fatigue, general fatigue, and the present three cases, respectively. The differences among the groups were not significant.